Fifteen bodies -- 14 of them border guards -- were found on May 30 on the Kazakh-Chinese frontier but there are still no clear answers as to how they died.

The facts, as they stand, are sketchy. What is known is that there was a fire at a remote outpost at Sary Bokter, in Almaty Oblast on the Kazakh-Chinese border. The fire burned down a soldiers' barracks and an officer's house and investigators found the bodies of the 14 border guards among the debris. The body of a civilian forest ranger was found shot to death in a nearby house. Officials have said that a 15th border guard, who was posted at the base, remains missing.

Several theories about the deaths have been aired in the Kazakh press: an accidental fire, an attack, or an incident connected to hazing.

The accidental fire theory has been called into some doubt, as investigators were quoted in the media as saying that the guards were already dead by the time the fire started.

The authorities have launched an investigation and the bodies have been taken to the Kazakh city of Astana for DNA identification and forensic tests. Officials have only said that preliminary tests show that none of the men had alcohol in their blood.

Kazakh President Nursultan Nazarbaev wasted no time in saying on June 1 that the apparent killings were “a terrorist act,” without specifying who might be behind it. His comments come during the trial of 37 people accused of organizing the mass unrest that led to deadly violence in the western Kazakh town of Zhanaozen last year.

If the deaths were the result of an attack, it is unclear who the perpetrators might be. The border, which is 1,520 kilometers long and entirely within China's Xin Jiang province, is relatively calm. As Nathan Hamm points out at "Registan":

If for no other reason, this incident is odd for having happened on the border with China. Violent incidents have not been uncommon along borders between Central Asian states or along Tajikistan’s border with Afghanistan. The Chinese border has been fairly quiet since independence.

The Sary Bokter border post is not permanent, but a temporary construction put up in the summer reportedly to clamp down on the scores of Chinese who cross the border to collect herbs and plants which are used in Chinese medicine. Despite that, it is not a region particularly blighted by ethnic or political tensions. (The fact that a border post was set up there to counter herb-pickers is testament to the relative low stakes.)

While no officials have gone on the record to accuse the Chinese, there have been mutterings in the press and on Internet forums about ethnic Chinese or Uyghur separatists being the likely culprits. This makes sense given the historical enmity and suspicion many Kazakhs hold for the Chinese. A Soviet-era proverb, loosely translated, reads: "If hordes of Chinese come, the red Russian will be like a father."

In recent years, there has been a rise in popular anti-China sentiment, after reports of official plans to lease Kazakh farmland to China. The presence of Chinese migrant laborers or market traders (both ethnic Uyghur and Han) across Kazakhstan has also stoked some resentments.

A Chinese hand here would seem far-fetched, considering the decent state of Kazakh-Chinese bilateral relations. And a remote outpost -- rather than, say, a crowded shopping mall -- would seem an unlikely target for domestic terrorism.

Skullduggery among smugglers is another possibility. Along some parts of the border, smugglers have operated freely. In 2011, there were reports that over 100 members of a criminal group had been arrested for illegally trafficking goods across the border.

The key to unraveling the mystery may well lie with the 15th border guard, who still has not been found -- along with a few missing horses. There has been speculation in the Kazakh press that it is the missing guard who is responsible for the killings, possibly as a revenge for hazing.

The sheer remoteness of the outpost (it is off the cellular grid) has just added to the confusion and speculation. But the Kazakh authorities are clearly taking the incident seriously. Border forces have been strengthened and on the highway between Almaty and Oskemen, military checkpoints have been put in place and cars have been stopped and searched. According to RFE/RL's Kazakh Service, local residents learned about the deaths from the press and many were scared to talk openly about the deaths.

President Nazarbaev has announced that June 5 will be a national day of mourning in Kazakhstan in honor of the slain border guards.